<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <!-- 标签选择器 影响范围大 一般用来做一些通用设置 -->
    <style>
        h1{
            color: red
        }

    </style>
</head>

<body>
<h1>test</h1>
<h1>test</h1>
</body>
</html>